One-pot solvothermal synthesis of singly doped Eu3+ and codoped Er3+, Yb3+ heavy rare earth oxysulfide Y2O2S nano-aggregates and their luminescence study

Abstract

Highly crystallized micro/nano-sized Y₂O₂S and RE (Eu³⁺, Yb³⁺/Er³⁺) doped samples were prepared through a one-pot mild (200–250 °C) solvothermal method. By simply adjusting the amount of initial sulfur powder, the morphology and assembled nano-structures could be well controlled. With varying concentration of sulfur powder from 0.08 M to 0.8 M, the morphology and size of the target products varied from 20 nm nanosheets, 2 μm sheet-assembled plates/flowers to 1.5 μm nano-assembled spheres. The luminescence properties of Eu³⁺ doped Y₂O₂S with different morphologies were studied. The excitation peak above 300 nm ascribed to S²⁻–Eu³⁺ charge transfer showed a blue shift of 9 nm compared with the bulk sample. When co-doped with Yb³⁺/Er³⁺, the Y₂O₂S:Yb³⁺, Er³⁺ nano-aggregates exhibited a tunable emission under 980 nm laser excitation, shifting from greenish-yellow to orange-yellow, with increasing Yb³⁺/Er³⁺ ratio.